Add external application pattern for private key file

Add external application pattern for private key file

I can currently open a PuTTY/KiTTY terminal for current connection passing the username and password.
However, for many sites I just have the private key.
While I can add those keys to Pageant/Kageant, our servers are set to reject connection after 3 failed key attempts.
With this feature request, WinSCP would allow me to pass the relevant private key that is used with the current connection to KiTTY's parameter -i.